目录
在一些软件，比如，进销存管理系统中添加销售单信息时，每个销售单都可能对应多种商品，而且在向销售单中添加商品时，一般都是在新弹出的窗体中选择商品，这时就涉及通过子窗体刷新父窗体的问题。
1、实现方法
实现通过子窗体刷新父窗体时，主要通过在自定义事件中执行数据绑定来对主窗体进行刷新，即当子窗体产生更新操作时，通过子窗体的一个方法触发主窗体中对应的事件，这个过程主要用到了EventHandler事件。
EventHandler事件主要是通过EventHandler委托来实现的，该委托表示处理不包含事件数据的事件的方法。语法格式如下：
public delegate void EventHandler(Object sender,EventArgs e)
参数说明
Sender：事件源。
e：不包含任何事件数据的EventArgs事件数据。例如，通过使用EventHandler事件为子窗体添加一个事件处理程序，以便能够刷新父窗体中的数据。
在子窗体里：
/// <summary>
/// 某一个事件，比如，添加
/// </summary>
private void Button1_Click(object? sender, EventArgs e)
{
GlobalFlag = true; //设定标识的值为true
if (!(comboBox1.Items.Equals(idContent))) //当Combobox控件中不存在将添加的信息时
{
comboBox1.Items.Add(idContent!); //在Combobox控件中添加一条记录
}
UpdateData();
}
// 其它
/// <summary>
/// 更新DataGridView控件中的内容
/// </summary>
protected void UpdateData()
{
UpdateDataGridView?.Invoke(this, EventArgs.Empty);
}在主窗体里：
// 添加子窗体的事件
public void CreateFrmChild()
{
Frm_Child BabyWindow = new()
{
MdiParent = this,
};
dataGridView1.Controls.Add(BabyWindow);
BabyWindow.UpdateDataGridView += new EventHandler(BabyWindow_UpdateDataGridView!);
BabyWindow.Show();
}
// 其它
/// <summary>
/// 实现事件委托
/// </summary>
void BabyWindow_UpdateDataGridView(object sender, EventArgs e)
{
// 其它
}2.SqlCommand类
本实例中使用了SQL，主窗体的数据读取自SQL，在子窗体里更新，然后回写SQL，其结果再次更新到主窗体。
在C#中执行SQL语句时，可以使用SqlCommand类，该类主要用于向SQL Server数据库发送SQL语句。
本实例的数据库连接字符串：
//数据库连接字符串
readonly string? ConnString = "Data Source=DESKTOP-3LV13FS;DataBase=db_TomeOne;integrated security=SSPI;TrustServerCertificate=true;";还有，在.NET 8.0中，要使用命名空间：using Microsoft.Data.SqlClient;因为 using System.Data.SqlClient; 已经废弃。
3.实例的主窗体Frm_Main：
（1）Frm_Main.Designer.cs
namespace _197
{
partial class Frm_Main
{
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null;
/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
#region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
menuStrip1 = new MenuStrip();
toolStripMenuItem1 = new ToolStripMenuItem();
toolStripMenuItem2 = new ToolStripMenuItem();
toolStripMenuItem3 = new ToolStripMenuItem();
dataGridView1 = new DataGridView();
menuStrip1.SuspendLayout();
((System.ComponentModel.ISupportInitialize)dataGridView1).BeginInit();
SuspendLayout();
//
// menuStrip1
//
menuStrip1.BackColor = SystemColors.ControlDark;
menuStrip1.Items.AddRange(new ToolStripItem[] { toolStripMenuItem1 });
menuStrip1.Location = new Point(0, 0);
menuStrip1.Name = "menuStrip1";
menuStrip1.Size = new Size(335, 25);
menuStrip1.TabIndex = 0;
menuStrip1.Text = "menuStrip1";
//
// toolStripMenuItem1
//
toolStripMenuItem1.DropDownItems.AddRange(new ToolStripItem[] { toolStripMenuItem2, toolStripMenuItem3 });
toolStripMenuItem1.Name = "toolStripMenuItem1";
toolStripMenuItem1.Size = new Size(44, 21);
toolStripMenuItem1.Text = "操作";
//
// toolStripMenuItem2
//
toolStripMenuItem2.Name = "toolStripMenuItem2";
toolStripMenuItem2.Size = new Size(136, 22);
toolStripMenuItem2.Text = "添加或删除";
toolStripMenuItem2.Click += ToolStripMenuItem2_Click;
//
// toolStripMenuItem3
//
toolStripMenuItem3.Name = "toolStripMenuItem3";
toolStripMenuItem3.Size = new Size(136, 22);
toolStripMenuItem3.Text = "退出";
toolStripMenuItem3.Click += ToolStripMenuItem3_Click;
//
// dataGridView1
//
dataGridView1.AllowUserToAddRows = false;
dataGridView1.ColumnHeadersHeightSizeMode = DataGridViewColumnHeadersHeightSizeMode.AutoSize;
dataGridView1.Dock = DockStyle.Fill;
dataGridView1.Location = new Point(0, 25);
dataGridView1.Name = "dataGridView1";
dataGridView1.Size = new Size(335, 178);
dataGridView1.TabIndex = 1;
//
// Frm_Main
//
AutoScaleDimensions = new SizeF(7F, 17F);
AutoScaleMode = AutoScaleMode.Font;
ClientSize = new Size(335, 203);
Controls.Add(dataGridView1);
Controls.Add(menuStrip1);
IsMdiContainer = true;
MainMenuStrip = menuStrip1;
Name = "Frm_Main";
Text = "主窗体";
Load += Frm_Main_Load;
menuStrip1.ResumeLayout(false);
menuStrip1.PerformLayout();
((System.ComponentModel.ISupportInitialize)dataGridView1).EndInit();
ResumeLayout(false);
PerformLayout();
}
#endregion
private MenuStrip menuStrip1;
private ToolStripMenuItem toolStripMenuItem1;
private ToolStripMenuItem toolStripMenuItem2;
private ToolStripMenuItem toolStripMenuItem3;
private DataGridView dataGridView1;
}
}
（2）Frm_Main.cs
// 通过子窗体刷新父窗体
// 设置主窗体的IsMdiContainer=true;
using System.Data;
using Microsoft.Data.SqlClient;
namespace _197
{
public partial class Frm_Main : Form
{
public Frm_Main()
{
InitializeComponent();
}
#region 声明的变量
private static bool flag = false; //标识是否创建新的子窗体
readonly Frm_Child BabyWindow = new();//实例化一个子窗体
readonly DataSet PubsSet = new(); //定义一个数据集对象
private static string[]? iDArray; //声明一个一维字符串数组
public DataTable? IDTable; //声明一个数据表对象
SqlDataAdapter? IDAdapter; //声明一个数据读取器对象
SqlDataAdapter? PubsAdapter; //声明一个数据读取器对象
SqlConnection? ConnPubs; //声明一个数据库连接对象
SqlCommand? PersonalInformation; //声明一个执行SQL语句的对象
public static string[]? IDArray { get => iDArray; set => iDArray = value; }
public static bool Flag { get => flag; set => flag = value; }
readonly string? ConnString //数据库连接字符串
= "Data Source=DESKTOP-3LV13FS;DataBase=db_TomeOne;integrated security=SSPI;TrustServerCertificate=true;";
#endregion
private void Frm_Main_Load(object? sender, EventArgs e)
{
string AdapterString = "select userID as 编号,userName as 姓名 ,phone as 电话,address as 住址 from tb_User";//用于查询的字符串
string IDString = "select userID from tb_User";//读取数据库中用户的ID编号字符串
ConnPubs = new SqlConnection(ConnString);//建立数据库连接
PubsAdapter = new SqlDataAdapter(AdapterString, ConnPubs);//创建PubsAdapter数据读取器
IDAdapter = new SqlDataAdapter(IDString, ConnPubs); //用于读取用户编号的读取器
PubsAdapter.Fill(PubsSet, "tb_User"); //填充PubsSet数据集
IDAdapter.Fill(PubsSet, "ID"); //填充PubsSet数据集
DataTable PubsTable = PubsSet.Tables["tb_User"]!;//将数据写入PubsTable表
IDTable = PubsSet.Tables["ID"]!; //将数据写入ID表
IDArray = new string[IDTable.Rows.Count]; //为数组定义最大长度
dataGridView1.DataSource = PubsTable.DefaultView;//设置dataGridView1的数据源
for (int i = 0; i < IDTable.Rows.Count; i++) //循环遍历数据表中的每一行数据
{
for (int j = 0; j < IDTable.Columns.Count; j++)//循环遍历数据表中的每一列数据
{
IDArray[i] = IDTable.Rows[i][j].ToString()!;//将数据表中的数据添加至一个一维数组
}
}
}
#region 创建子窗体的CreateFrmChild方法
/// <summary>
/// 设置子窗体的父窗体为当前窗体;
/// 实例化一个子窗体;
/// 在DataGridView控件中添加子窗体;
/// 显示子窗体;
/// </summary>
public void CreateFrmChild()
{
Frm_Child BabyWindow = new()
{
MdiParent = this,
};
dataGridView1.Controls.Add(BabyWindow);
BabyWindow.UpdateDataGridView += new EventHandler(BabyWindow_UpdateDataGridView!);
BabyWindow.Show();
}
/// <summary>
/// 事件委托
/// </summary>
void BabyWindow_UpdateDataGridView(object sender, EventArgs e)
{
if (Frm_Child.GlobalFlag == false) //当单击删除按钮时
{
if (ConnPubs!.State == ConnectionState.Closed) //当数据库处于断开状态时
{
ConnPubs.Open(); //打开数据库的连接
}
string AfreshString = "delete tb_User where userID=" + Frm_Child.DeleteID!.Trim();//定义一个删除数据的字符串
PersonalInformation = new SqlCommand(AfreshString, ConnPubs); //执行删除数据库字段
PersonalInformation.ExecuteNonQuery(); //执行SQL语句并返回受影响的行数
ConnPubs.Close(); //关闭数据库
DisplayData(); //显示数据库更新后的内容
MessageBox.Show("数据删除成功！", "提示信息", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
}
else
{
if (ConnPubs!.State == ConnectionState.Closed) //当数据库处于关闭状态时
{
ConnPubs.Open(); //打开数据库
}
string InsertString = "insert into tb_User values('" + Frm_Child.IdContent + "','" + Frm_Child.NameContent + "','" + Frm_Child.PhoneContent + "','" + Frm_Child.AddressContent + "')";//定义一个插入数据的字符串变量
PersonalInformation = new SqlCommand(InsertString, ConnPubs);//执行插入数据库字段
PersonalInformation.ExecuteNonQuery(); //执行SQL语句并返回受影响的行数
ConnPubs.Close(); //关闭数据库
DisplayData(); //显示更新后的数据
MessageBox.Show("数据添加成功！", "提示信息", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
}
}
#endregion
#region 用于读取数据库的DisplayData方法
public void DisplayData()
{
PubsSet.Clear();
ConnPubs = new SqlConnection(ConnString);
string DisplayString = "select userId as 编号,userName as 姓名 ,phone as 电话,address as 住址 from tb_User";//定义读取数据库的字段
SqlDataAdapter PersonalAdapter = new(DisplayString, ConnPubs); //定义一个读取数据库数据的读取器
PersonalAdapter.Fill(PubsSet, "tb_User"); //向表DisplayTable中填充数据
dataGridView1.DataSource = PubsSet.Tables["tb_User"]!.DefaultView; //设定DataGridView控件的数据源
}
#endregion
/// <summary>
/// 添加或删除记录
/// 创建子窗体的CreateFrmChild方法
/// </summary>
private void ToolStripMenuItem2_Click(object sender, EventArgs e)
{
if (flag == false) //判断标识的值决定是否创建窗体
{
CreateFrmChild();//创建子窗体
}
for (int i = 0; i < dataGridView1.Controls.Count; i++) //循环遍历DataGridView控件上的控件集
{
if (dataGridView1.Controls[i].Name.Equals(BabyWindow.Name)) //当存在子窗体时
{
flag = true; //改变标识Flag的值
break; //退出循环体
}
}
}
/// <summary>
/// 退出
/// </summary>
private void ToolStripMenuItem3_Click(object sender, EventArgs e)
{
Application.Exit();
}
}
}
4.实例的子窗体Frm_Child：
（1） Frm_Child.Designer.cs
namespace _197
{
partial class Frm_Child
{
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null;
/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
protected override void Dispose(bool disposing)
{
if (disposing && (components != null))
{
components.Dispose();
}
base.Dispose(disposing);
}
#region Windows Form Designer generated code
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
groupBox1 = new GroupBox();
button2 = new Button();
button1 = new Button();
Record_Address = new TextBox();
Record_Phone = new TextBox();
Record_Name = new TextBox();
Record_ID = new TextBox();
label4 = new Label();
label3 = new Label();
label2 = new Label();
label1 = new Label();
groupBox2 = new GroupBox();
button3 = new Button();
comboBox1 = new ComboBox();
label5 = new Label();
groupBox1.SuspendLayout();
groupBox2.SuspendLayout();
SuspendLayout();
//
// groupBox1
//
groupBox1.Controls.Add(button2);
groupBox1.Controls.Add(button1);
groupBox1.Controls.Add(Record_Address);
groupBox1.Controls.Add(Record_Phone);
groupBox1.Controls.Add(Record_Name);
groupBox1.Controls.Add(Record_ID);
groupBox1.Controls.Add(label4);
groupBox1.Controls.Add(label3);
groupBox1.Controls.Add(label2);
groupBox1.Controls.Add(label1);
groupBox1.Location = new Point(12, 12);
groupBox1.Name = "groupBox1";
groupBox1.Size = new Size(270, 157);
groupBox1.TabIndex = 0;
groupBox1.TabStop = false;
groupBox1.Text = "添加信息";
//
// button2
//
button2.Location = new Point(187, 56);
button2.Name = "button2";
button2.Size = new Size(75, 23);
button2.TabIndex = 9;
button2.Text = "清空";
button2.UseVisualStyleBackColor = true;
button2.Click += Button2_Click;
//
// button1
//
button1.Location = new Point(187, 25);
button1.Name = "button1";
button1.Size = new Size(77, 23);
button1.TabIndex = 8;
button1.Text = "提交";
button1.UseVisualStyleBackColor = true;
button1.Click += Button1_Click;
//
// Record_Address
//
Record_Address.Location = new Point(72, 118);
Record_Address.Name = "Record_Address";
Record_Address.Size = new Size(100, 23);
Record_Address.TabIndex = 7;
Record_Address.TextChanged += Record_Address_TextChanged;
//
// Record_Phone
//
Record_Phone.Location = new Point(72, 87);
Record_Phone.Name = "Record_Phone";
Record_Phone.Size = new Size(100, 23);
Record_Phone.TabIndex = 6;
Record_Phone.TextChanged += Record_Phone_TextChanged;
//
// Record_Name
//
Record_Name.Location = new Point(72, 56);
Record_Name.Name = "Record_Name";
Record_Name.Size = new Size(100, 23);
Record_Name.TabIndex = 5;
Record_Name.TextChanged += Record_Name_TextChanged;
//
// Record_ID
//
Record_ID.Location = new Point(72, 25);
Record_ID.Name = "Record_ID";
Record_ID.Size = new Size(100, 23);
Record_ID.TabIndex = 4;
Record_ID.TextChanged += Record_ID_TextChanged;
//
// label4
//
label4.AutoSize = true;
label4.Location = new Point(11, 118);
label4.Name = "label4";
label4.Size = new Size(44, 17);
label4.TabIndex = 3;
label4.Text = "地址：";
//
// label3
//
label3.AutoSize = true;
label3.Location = new Point(11, 87);
label3.Name = "label3";
label3.Size = new Size(44, 17);
label3.TabIndex = 2;
label3.Text = "电话：";
//
// label2
//
label2.AutoSize = true;
label2.Location = new Point(11, 56);
label2.Name = "label2";
label2.Size = new Size(44, 17);
label2.TabIndex = 1;
label2.Text = "姓名：";
//
// label1
//
label1.AutoSize = true;
label1.Location = new Point(11, 25);
label1.Name = "label1";
label1.Size = new Size(44, 17);
label1.TabIndex = 0;
label1.Text = "编号：";
//
// groupBox2
//
groupBox2.Controls.Add(button3);
groupBox2.Controls.Add(comboBox1);
groupBox2.Controls.Add(label5);
groupBox2.Location = new Point(12, 175);
groupBox2.Name = "groupBox2";
groupBox2.Size = new Size(270, 54);
groupBox2.TabIndex = 1;
groupBox2.TabStop = false;
groupBox2.Text = "删除信息";
//
// button3
//
button3.Location = new Point(187, 24);
button3.Name = "button3";
button3.Size = new Size(75, 23);
button3.TabIndex = 2;
button3.Text = "删除";
button3.UseVisualStyleBackColor = true;
button3.Click += Button3_Click;
//
// comboBox1
//
comboBox1.FormattingEnabled = true;
comboBox1.Location = new Point(72, 24);
comboBox1.Name = "comboBox1";
comboBox1.Size = new Size(100, 25);
comboBox1.TabIndex = 1;
//
// label5
//
label5.AutoSize = true;
label5.Location = new Point(11, 30);
label5.Name = "label5";
label5.Size = new Size(44, 17);
label5.TabIndex = 0;
label5.Text = "编号：";
//
// Frm_Child
//
AutoScaleDimensions = new SizeF(7F, 17F);
AutoScaleMode = AutoScaleMode.Font;
ClientSize = new Size(294, 241);
Controls.Add(groupBox2);
Controls.Add(groupBox1);
MaximizeBox = false; //最大化按钮没有意义
Name = "Frm_Child";
StartPosition = FormStartPosition.CenterScreen;
Text = "子窗体";
FormClosing += Frm_Child_FormClosing;
Load += Frm_Child_Load;
groupBox1.ResumeLayout(false);
groupBox1.PerformLayout();
groupBox2.ResumeLayout(false);
groupBox2.PerformLayout();
ResumeLayout(false);
}
#endregion
private GroupBox groupBox1;
private TextBox Record_Address;
private TextBox Record_Phone;
private TextBox Record_Name;
private TextBox Record_ID;
private Label label4;
private Label label3;
private Label label2;
private Label label1;
private GroupBox groupBox2;
private Button button2;
private Button button1;
private Button button3;
private ComboBox comboBox1;
private Label label5;
}
}（2）Frm_Child.cs
// 本实例仅可创建一个窗口:
// 最大化后没有实际意义，因此关闭MaximizeBox属性值为False
namespace _197
{
public partial class Frm_Child : Form
{
#region 变量的声明
public event EventHandler? UpdateDataGridView = null;//定义一个处理更新DataGridView控件内容的方法
private static string? deleteID; //定义一个表示删除数据编号的字符串
private static string? idContent; //该变量用来存储数据编号
private static string? nameContent; //该变量用来存储姓名
private static string? phoneContent; //该变量用来存储电话
private static string? addressContent; //该变量用来存储住址
private static bool globalFlag; //该变量用来标识是否创建新的子窗体
public static string? DeleteID { get => deleteID; set => deleteID = value; }
public static string? IdContent { get => idContent; set => idContent = value; }
public static string? NameContent { get => nameContent; set => nameContent = value; }
public static string? PhoneContent { get => phoneContent; set => phoneContent = value; }
public static string? AddressContent { get => addressContent; set => addressContent = value; }
public static bool GlobalFlag { get => globalFlag; set => globalFlag = value; }
#endregion
public Frm_Child()
{
InitializeComponent();
}
/// <summary>
/// 添加
/// </summary>
private void Button1_Click(object? sender, EventArgs e)
{
GlobalFlag = true; //设定标识的值为true
if (!(comboBox1.Items.Equals(idContent))) //当Combobox控件中不存在将添加的信息时
{
comboBox1.Items.Add(idContent!); //在Combobox控件中添加一条记录
}
UpdateData();
}
/// <summary>
/// 清空
/// </summary>
private void Button2_Click(object? sender, EventArgs e)
{
Record_ID.Clear(); //清空编号文本框中的内容
Record_Name.Clear(); //清空姓名文本框中的内容
Record_Phone.Clear(); //清空电话号码文本框中的内容
Record_Address.Clear(); //清空居住地址文本框中的内容
Record_ID.Focus(); //设定当前鼠标的焦点在编号文本框中
}
/// <summary>
/// 删除
/// </summary>
private void Button3_Click(object? sender, EventArgs e)
{
GlobalFlag = false; //设定全局变量表示为false
if (comboBox1.Items.Count > 1) //当ComboBox中剩不小于2条内容时
{
DeleteID = comboBox1.SelectedItem!.ToString(); //将选中项转化为int型
if (comboBox1.Items.Count != 0) //当ComboBox中剩1条内容时
{
comboBox1.Items.Remove(comboBox1.SelectedItem);
comboBox1.SelectedIndex = 0;
}
}
UpdateData();
}
/// <summary>
/// 保存新添加记录的编号
/// </summary>
private void Record_ID_TextChanged(object? sender, EventArgs e)
{
idContent = Record_ID.Text;
}
/// <summary>
/// 保存填入的姓名
/// </summary>
private void Record_Name_TextChanged(object? sender, EventArgs e)
{
nameContent = Record_Name.Text;
}
/// <summary>
/// 保存填入的电话号码
/// </summary>
private void Record_Phone_TextChanged(object? sender, EventArgs e)
{
phoneContent = Record_Phone.Text;
}
/// <summary>
/// 保存填入的地址信息
/// </summary>
private void Record_Address_TextChanged(object? sender, EventArgs e)
{
addressContent = Record_Address.Text;
}
/// <summary>
/// 循环遍历数组中的每一个元素,向Combobox控件中添加内容
/// 默认设定当前选中项的索引为0
/// </summary>
private void Frm_Child_Load(object? sender, EventArgs e)
{
for (int i = 0; i < Frm_Main.IDArray!.Length; i++)
{
comboBox1.Items.Add(Frm_Main.IDArray[i].ToString());
comboBox1.SelectedIndex = 0;
}
}
/// <summary>
/// 设定该值为false表示可以创建新窗体
/// </summary>
private void Frm_Child_FormClosing(object? sender, FormClosingEventArgs e)
{
Frm_Main.Flag = false;
}
/// <summary>
/// 更新DataGridView控件中的内容
/// </summary>
protected void UpdateData()
{
UpdateDataGridView?.Invoke(this, EventArgs.Empty);
}
}
}
5.生成效果
（1）生成
（2）添加
（3）添加后
（4）清空